There are three classes of phosphoinositide-3-kinases (PI3Ks): class I, class II and class III. Class I PI3Ks are the most associated with human cancer [K. D Courtney, R. B. Corcoran and J. A. Engelman (2010), Journal of Clinical Oncology., 28; 1075]. The class I phosphoinositide-3-kinases (PI3Ks) are divided into 2 subclasses: class IA, composed of a p110 catalytic subunit (p110a, p110b or p110d) and a p85 regulatory subunit (p85a, p55a and p50a, p85b or p55g) and class IB PI3K represented by the p110g catalytic subunit and the p101 and p84 regulatory subunits [B. Vanhaesebroeck and M. D. Waterfield (1999) Experimental Cell Research., 253, 239-254]. The class IA PI3Ks are activated in a variety of solid and non-solid tumors via mutation or deletion of the tumor suppressor PTEN (phosphatase and tensin homolog) or in the case of p110a by activating mutations [K. D Courtney, R. B. Corcoran and J. A. Engelman (2010), Journal of Clinical Oncology, 28; 1075]. PI3Ks can also be activated by receptor tyrosine kinases (RTKs); p110b can be activated by G-protein coupled receptors [K. D Courtney, R. B. Corcoran and J. A. Engelman (2010), Journal of Clinical Oncology., 28; 1075]. Once activated the phosphoinositide-3-kinases catalyze the phosphorylation of phosphatidyl 4,5-diphosphate leading to the generation of phosphatidyl, 3,4,5-triphosphate (PIP3) [Zhao L., Vogt P. K. (2008) Oncogene 27, 5486-5496]. PTEN antagonizes the activity of the PI3Ks through the dephosphorylation PIP3 [Myers M. P., Pass I., Batty I. H., Van der Kaay J., Stolarov J. P., Hemmings B. A., Wigler M. H., Downes C. P., Tonks N. K. (1998) Proc. Natl. Acad. Sci. U.S.A. 95, 13513-13518]. The PIP3 generated by activation of PI3K or sustained by the inactivation of PTEN binds to a subset of lipid-binding domains in downstream targets such as the pleckstrin homology domain of the oncogene Akt thereby recruiting it to the plasma membrane [Stokoe D., Stephens L. R., Copeland T., Gaffney P. R., Reese C. B., Painter G. F., Holmes A. B., McCormick F., Hawkins P. T. (1997) Science 277, 567-570]. Once at the plasma membrane Akt phosphorylates several effector molecules that are involved in numerous biologically relevant processes such as metabolism, differentiation, proliferation, longevity and apoptosis [D. R. Calnan and A. Brunet (2008) Oncogene 27; 2276)].
Several studies suggest a key role for p110b in PTEN-deficient tumors. For example the genetic knockout of p110b, but not p110a, is able to block tumor formation and Akt activation driven by Pten loss in the anterior prostate in a mouse model [Jia S, Liu Z, Zhang S. Liu P, Zhang L, Lee S H, Zhang J, Signoretti S, Loda M, Roberts T M, Zhao J J. Nature 2008; 454:776-9]. Furthermore other studies have shown that a subset of PTEN-deficient human tumor cell lines is sensitive to inactivation of p110b rather than p110a [Wee S. Wiederschain D. Maira S M, Loo A, Miller C, deBeaumont R, Stegmeier F, Yao Y M, Lengauer C (2008) Proc. Natl. Acad. Sci (USA); 105 13057]. PTEN deficiency either by genetic inactivation or reduced expression frequently occurs in human cancers such as GBM, endometrial, lung, breast cancers and prostate cancer among others [K. D Courtney, R. B. Corcoran and J. A. Engelman (2010), Journal of Clinical Oncology., 28; 1075].
These studies suggest that treatment of PTEN-deficient cancer with agents that inhibition p110b may be therapeutically beneficial. In addition to its role in cancer, p110b may be a target for antithrombotic therapy. It has been reported in mouse models that PI3Kb inhibition can prevent stable integrin aIIbb3 adhesion contacts that eliminates occulusive thrombus formation without prolongation of bleed time [S. P. Jackson et al. (2005) Nature Medicine., 11, 507-514].
Furthermore, the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT pathway is frequently activated during prostate cancer (PCa) progression through loss or mutation of the phosphatase and tensin homolog (PTEN) gene. Following the androgen receptor (AR) pathway, it is the second major driver of PCa growth. Combination with hormonal therapy improved efficacy of PI3K/AKT-targeted agents in PTEN-negative PCa models. Upregulation of AR-target genes upon PI3K/AKT inhibition suggests a compensatory crosstalk between the PI3K-AR pathways which, for optimal efficacy treatment, could require cotargeting of the AR axis [Marques R B, et al., High Efficacy of Combination Therapy Using PI3K/AKT Inhibitors with Androgen Deprivation in Prostate Cancer Preclinical Models. Eur Urol (2014), http://dx.doi.org/10.1016/j.eururo.2014.08.053]. Therefore PI3Kβ inhibitors can be advantageously combined with anti-androgen therapies including androgen receptor antagonists and inhibitors of androgen biosynthesis in PTEN-negative prostate cancers.
WO 2009/060197 discloses imidazopyridazines for use as protein kinase inhibitors.
WO 2012/116237 discloses heterocyclic entitites that modulate PI3 kinase activity.
WO 2011/123751 describes heterocyclic compounds as selective inhibitors of PI3K activity.
WO 2011/058109 relates to a series of fused bicyclic pyrrole and imidazole derivatives as kinase inhibitors.
WO 2011/022439 discloses heterocyclic entities that modulate PI3 kinase activity.
WO 2008/014219 describes thiozolidinedione derivatives as PI3 kinase inhibitors.
WO 2013/028263 relates to pyrazolopyrimidine derivatives as PI3 kinase inhibitors.
WO 2012/047538 relates to benzimidazole derivatives as PI3 kinase inhibitors.
WO 2013/095761 relates to imidazopyridine derivatives as PI3 kinase inhibitors.
US 2013/0157977 relates to benzimidazole boronic acid derivatives as PI3 kinase inhibitors.
WO2007/038314 discloses heterocyclic compounds useful as kinase modulators.
WO2008/030579 describes modulators of IRAK kinase.
WO2009/091374 and WO2008/008539 relate to fused heterocyclic derivatives for prophylaxis and treatment of diseases, such as HGF mediated diseases.
WO 2014/078211 discloses heteroaromatic compounds as PI3 kinase modulators.
WO 2008/138834 relates to substituted imidazopyridazines as PI3K lipid kinase inhibitors.
WO 2010/007099 describes 2-aminoimidazo[1,2-b]pyridazine derivatives as PI3K inhibitors.
WO 2011/047770 discloses pyrazolopyrimidine derivatives as PI3K inhibitors.
There is thus a strong need for novel PI3Kβ kinase inhibitors thereby opening new avenues for the treatment or prevention of cancer, in particular PTEN-deficient cancers, more in particular prostate cancer. It is accordingly an object of the present invention to provide such compounds.